This invention relates generally to pressurized fluid-containing apparatuses and devices and, more particularly, to such an apparatus or device used in the inflation of an inflatable device such as an inflatable vehicle occupant restraint airbag cushion used in inflatable restraint systems.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an "airbag cushion," that is inflated or expanded with gas when the vehicle encounters sudden deceleration, such as in a collision. In such systems, the airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins to be inflated, in a matter of no more than a few milliseconds, with gas produced or supplied by a device commonly referred to as "an inflator."
Many types of inflator devices have been disclosed in the art for the inflating of one or more inflatable restraint system airbag cushions. Prior art inflator devices include compressed stored gas inflators, pyrotechnic inflators and hybrid inflators. Unfortunately, each of these types of inflator devices has been subject to certain disadvantages such as greater than desired weight and space requirements, production of undesired or non-preferred combustion products in greater than desired amounts, and production or emission of gases at a greater than desired temperature, for example.
In view of these and other related or similar problems and shortcomings of prior inflator devices, a new type of inflator, called a "fluid fueled inflator," has been developed. Such inflators are the subject of commonly assigned Smith et al., U.S. Pat. No. 5,470,104, issued Nov. 28, 1995; Rink, U.S. Pat. No. 5,494,312, issued Feb. 27, 1996; and Rink et al., U.S. Pat. No. 5,531,473, issued Jul. 2, 1996, the disclosures of which are fully incorporated herein by reference.
Such inflator devices typically utilize a fuel material in the form of a fluid, e.g., in the form of a gas, liquid, finely divided solid, or one or more combinations thereof, in the formation of an inflation gas for an airbag. In one such inflator device, the fluid fuel material is burned to produce gas which contacts a quantity of stored pressurized gas to produce inflation gas for use in inflating a respective inflatable device.
While such an inflator can successfully overcome, at least in part, some of the problems commonly associated with the above-identified prior types of inflator devices, there is a continuing need and demand for further improvements in safety, simplicity, effectiveness, economy and reliability in the apparatus and techniques used for inflating an inflatable device such as an airbag cushion.
To that end, the above-identified Rink, U.S. Pat. No. 5,669,629 discloses a new type of inflator wherein a gas source material undergoes decomposition to form decomposition products including at least one gaseous decomposition product used to inflate an inflatable device.
Such an inflator can be helpful in one or more of the following respects: reduction or minimization of concerns regarding the handling of content materials; production of relatively low temperature, non-harmful inflation gases; reduction or minimization of size and space requirements and avoidance or minimization of the risks or dangers of the gas producing or forming materials undergoing degradation (thermal or otherwise) over time as the inflator awaits activation.
Nevertheless, there is a need and demand for yet still further improvements in safety, simplicity, effectiveness, economy and reliability in the apparatus and techniques used for inflating an inflatable device such as an airbag cushion.
For example, it is common in prior inflator devices to have one or more preformed openings or passages with each such opening or passage normally covered or blocked by a device, such as a burst disc or the like, until such time as when flow through the opening or passage is desired. As a result of the use of a separate covering or blocking device, the number of component parts may be greater than desired for optimal handling and manufacture and the risks associated with the formation of leak paths from an inflator device pressure vessel may be greater than desired. In addition, current inflator assembly designs commonly weld such burst discs or the like in place. Unfortunately, welding can be a relatively expensive manufacturing process. For proper welding, the surface conditions of the components to be joined must usually be well controlled in terms of geometric tolerances and surface cleanliness. Further, the equipment needed or used in such weld processing can be expensive to purchase and maintain. Still further, weld processing is typically a source of high scrap rates in high volume production programs.
Consequently, there is a need and a demand for still further reductions in the number of inflator component parts such as through the elimination of a burst disc or the like and for inflator assemblies which can simplify manufacture and avoid or minimize the risks of possibly forming leak paths from the pressure vessel. In particular, there is a need and demand for an improved inflator apparatus such as may be helpful in either or both reducing or simplifying the number or types of component parts and manufacturing process steps. Further, there is a need and demand for an improved pressurized inflator apparatus which reduces or minimizes the possible number of leak paths and thus may result in improved reliability and simplified manufacture and production.